This invention relates generally to a single use syringe device and more specifically to a syringe device having an integral locking mechanism to prevent extraction of the plunger after use.
The increasing awareness of the importance of sterility in hypodermic devices has led to the advent of disposable syringes. The initial sterility, coupled with their low cost, has led to the widespread use of these devices in preference over reusable devices requiring sterilization before reuse. But the widespread use of disposable syringes has created problems. By their economic nature, inexpensive devices, utilized in high numbers, tend to make inventory controls on new and used devices difficult and prone to breakdown It is not uncommon for syringes, along with the attached needles, to find their way into unauthorized hands. Once control is lost, these devices may be reused without sterilization.
Reuse of hypodermic syringes, intended for a single use only, is instrumental in the transfer of contagious diseases and facilitation of drug abuse. Intravenous drug users who routinely share and reuse syringes are a high risk group with respect to the HIV and hepatitis virii. Easy access to the devices further facilitates illegal drug use. In addition, the effects of repeated uses of syringe products may be responsible for the spread of many other diseases.
One solution to these problems is to develop syringes which functionally self-destruct after a single application. While non-reusable syringes will not necessarily stop illegal drug use, it can prevent sharing of contaminated hypodermic syringes and thus help reduce the spread of diseases.
Many approaches have been made to prevent and limit reuse. Initially, syringe designs incorporated features facilitating an explicit destructive act. Thus, by the application of force, the syringe becomes inoperable. Other designs included special structures to lock the device in a position preventing reuse. Some designs utilized locks incorporated in the barrel section of the syringe, requiring full extension to engage the device. Other designs require the syringe to be prefilled, and may not be filled in the conventional manner. Additional designs require multiple parts and careful assembly.
The ideal syringe design would incorporate a locking mechanism that would allow conventional use of the syringe (i.e. normal filling operations). In addition, the design would be simple to operate, not requiring any special training. The design should be able to utilize standard hypodermic needles. The design should be inexpensive and reliable. Finally, the design should encourage the full and complete elimination of valuable medication.